The patio gas bomb defused in Haymarket would have generated a fireball the size of a house and a shock wave spreading out over a diameter of at least 400 yards, explosives experts said today.

The propane cylinders and petrol used in the device would have triggered a huge conflagration, as well as causing shrapnel and blast injuries from the exploding car chassis and the nails packed around the bomb, according to Hans Michels, Professor of Safety Engineering at Imperial College, London.

Just one 13kg propane canister  the type sold by Calor under the brand name Patio Gas  would release a highly flammable cloud of vapour that would spread over an area of 50 to 60 cubic metres before igniting into a still larger fireball, he said.

The vapour cloud from one cylinder would fill the order of a big room, and when it ignited the effect would be even bigger, Professor Michels said. In addition to the power of the explosion and the shrapnel, you would get a fireball the size of a small house.

As several propane or butane cylinders were recovered, the volume of the fireball would have been greater still, though it is impossible to calculate the size without knowing how much gas would have been involved.

Professor Michels, who has been an expert witness in explosives trials, said that although the police did not say whether high explosives were found in the car, another charge would probably have been used to ignite the petrol and gas.

An initiator such as triacetone triperoxide or TATP could have been used to detonate a main charge, such as the flour and hydrogen peroxide mixture allegedly used in the failed attacks of July 21, 2005. This would have blown up the car, scattering nails and shrapnel, as well as igniting the petrol and puncturing the gas cylinders.

The gas-fuelled fireball would have followed, though the timing of ignition would have affected the ultimate extent of the blast. It is possible that the petrol was intended as the main charge, but if so this would have resulted in a smaller explosion than if high explosive had been used.

The original explosion would have had to be large to penetrate the propane canisters, which are designed to withstand high-speed traffic accidents and fires.

Professor Michels said: It is almost certain that the explosive device itself would have been sufficiently powerful not to just fragment the gas cylinders, but to destroy the car and possibly the front of buildings, with missiles, shrapnel, nails and burning petrol flung at very high velocity in the wake of the shock wave and the whole surrounded by a massive fireball resulting from the instantly evaporated and exploded propane and/or butane.

It is also likely that the source of ignition and the explosive that should have set off the device was of the home made type, consisting of household materials now most commonly used by terrorists.

Other experts suggested that the total blast could have been bigger still, depending on how many propane cylinders ignited and on whether high explosive was also used.

Andy Oppenheimer, editor of Nuclear, Biological and Chemical International, said the blast radius could have been anything from 200 years to half a mile. It would have been a devastating explosion, he said.

With that amount of petrol and an unknown quantity of pressurised gas, the blast would have been about 200 yards. If high explosive was involved, the blast could have reached half a mile.

Hundreds of people could have been injured if they had been in the area at the time. The knock-on effects of breaking glass are particularly devastating, for example.

This would have been an explosion on the scale of those seen in the Middle East, although not as big as some that have been seen in Baghdad recently.

The recovery of the intact bomb will also help forensic scientists to trace the bomb-makers, Professor Michels said. Propane cylinders carry a serial number which can be used to find the point of sale, and isotopic analysis could be used to trace any flour used in the main explosive charge.

Propane cylinders contain liquified propane, a volatile hydrocarbon, which would rapidly be transformed into a gas occupying 200 to 400 times the volume when released. This would mix with between 15 and 20 times that volume of air to produce an inflammable vapour cloud.

Brian Baker, director of the Association For Petroleum And Explosives Administration, said: Propane is liquefied petroleum gas and patio heater gas is usually 97 per cent propane. Cylinders of this type of gas are readily available to the public and can be bought in places such as petrol stations and iron monger in particular.

Propane is heavier than air when released, highly flammable and easy to ignite. When released in to the atmosphere and only a small amount is a required to cause an explosive condition and this is worse in a confined space when subject to an ignition source. Its explosive properties mean that 10 litres of the gas is equivalent to 2770 litres of flammable gas and air mix. There are controls on using this type of gas and this is why the industry gives lots of safety advice about use.

Propane is heavier than air when released, highly flammable and easy to ignite. When released in to the atmosphere and only a small amount is a required to cause an explosive condition and this is worse in a confined space when subject to an ignition source. Its explosive properties mean that 10 litres of the gas is equivalent to 2770 litres of flammable gas and air mix. There are controls on using this type of gas and this is why the industry gives lots of safety advice about use.

This can only mean one thing. Brits and Aussies will have to give up their grills, and Americans will be required (initially) to register them with the State Police in their respective jurisdictions.

This is a test to see how the new Prime Minister is going to react. I’ll bet that AlQueda sends a message to the UK to the effect that: This is what could happen, we are here. So give up and make nice or else.

The first car, which was parked under a blue awning near the popular Tiger Tiger nightclub, just 50 yards from Trafalgar Square, was jammed with gasoline and 18 to 20 boxes of roofing nails. Six to eight tanks of propane, intended to mix with the gasoline in a mist to make a fuel-air explosion, were inside and around the car, counterterrorism officials told NBC News.

Clarke told reporters that the second car was similarly laden with explosives and nails.

U.S. officials told NBC that the devices appeared designed to create a highly explosive bomb of the type that had been seen in Iraq but not, until now, in the West.

Islamist terrorist suspects convicted in recent London cases have spoken of moving up to more deadly fuel-air explosives, authorities said. Metropolitan Police Commissioner Ian Blair said earlier this year that vehicle-borne weaponry is the greatest danger that we can face.

"This can only mean one thing. Brits and Aussies will have to give up their grills, and Americans will be required (initially) to register them with the State Police in their respective jurisdictions."

I believe you're forgetting one thing. The Brit's use of surveillance cameras in identifying and apprehending the perp will result in the the call for federally funded and monitored CCTV cameras every 100 ft. throughout the continental US (with the exception of a 50-mile exclusion zone along the US/Mex border.)

Andy Oppenheimer, editor of Nuclear, Biological and Chemical International, said the blast radius could have been anything from 200 years to half a mile. It would have been a devastating explosion, he said.

Wow... that is really something!

12
posted on 06/29/2007 1:54:32 PM PDT
by abner
(I have no tagline, therefore no identity.)

...Police were alerted by an ambulance crew who saw smoke coming from the silver Mercedes, parked near the Tiger Tiger nightclub.

"International elements" are believed to be involved, the BBC has been told.

Police sources say it is quite possible the device failed to ignite - and might have been minutes away from exploding.

Deputy Assistant Commissioner Peter Clarke, head of Scotland Yard's counter-terrorism command, said: "It is obvious that if the device had detonated there could have been serious injury or loss of life."...

18
posted on 06/29/2007 1:58:57 PM PDT
by 3AngelaD
(They screwed up their own countries so bad they had to leave, and now they're here screwing up ours)

The first car, which was parked under a blue awning near the popular Tiger Tiger nightclub, just 50 yards from Trafalgar Square, was jammed with gasoline and 18 to 20 boxes of roofing nails. Six to eight tanks of propane, intended to mix with the gasoline in a mist to make a fuel-air explosion, were inside and around the car, counterterrorism officials told NBC News.

I'm starting to get the impression that these people aren't at all concerned about their carbon footprint.

Consider too that the terrorists call the cell phone twice, trying to set off the bomb.

This is something I've been trying to get clarification on.

I wanted to find out the time and date of the calls they report, to know if they were called after the driver ditched the car, of if they were called before this to test device before the trigger went live.

As they were most likely using a clean prepaid cellphone with no history, "two missed calls" on the screen may not reveal the whole picture without the specifics.

If anyone has more info, please fill me in.

31
posted on 06/29/2007 2:09:17 PM PDT
by USF
(I see your Jihad and raise you a Crusade)

~snip~
“British police have a “crystal clear” picture of the man who drove the bomb-rigged silver Mercedes outside a London nightclub, and officials tell the Blotter on ABCNews.com he bears “a close resemblance” to a man arrested by police in connection with another bomb plot but released for lack of evidence. Officials say the suspect had been taken into custody in connection with the case of al Qaeda operative Dhiren Barot (pictured), who was convicted of orchestrating a vehicle bomb plot involving targets in London, New York, Newark, N.J. and Washington, D.C.

~snip~
U.S. and British law enforcement officials tell ABC News it is increasingly clear Friday’s bomb plot in London involves multliple vehicles, and is described by a senior official as a “terror plot involving lslamic extremists.”

The flammable (explosive) limits for propane are 2.3 to 9.5%. If there was “too much” propane no explosion. If you were in a room with 15% propane and lit a match, nothing would happen! (Well, you’d pass out from breathing all the propane).

The intent of the designers may have been a vapor explosion, but it takes some careful design to actually get one. The vapor must be mixed with air so that the above limits are met, then set off with multiple sources.

The device would have made a big fire for absolute certain, but the huge vapor explosion is speculation.

My intent here is not to make light of the situation, but the “journalist” is inflating the magnitude of the threat unless he has some detailed information on the car bomb’s design, which has been labeled “crude”. The professor quoted in the article does not even know if there was any high explosive in the car, or a detonator, yet he assumes huge FAB- type explosions.

That understates the real damage - especially if the bomb is packed with screws, nail and wafarin - yes, rat poison. Any one within range who isn't killed gets to live out the rest of their lives in debilitating agony. This would have been truly catastrophic had it went off.

"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelologus

Pure hydrogen peroxide (not the 3% stuff in the drug store) is nasty stuff that decays to water and pure oxygen. Mix pure oxygen with something flammable and powdered like flour and your get a big boom.

Thanks... the reason why I wanted to know was I still think it odd they would attack Tiger Tiger on a Thursday night, and not a Friday or Sat night when they are usually packed (see my comments in this thread: http://www.freerepublic.com/focus/news/1858162/posts).

The exact circumstances of the calls would give us a clearer picture of the plot - if they screwed up getting multiple assets (some of which may still be out there) into place last night for a more devastating Friday night attack.

41
posted on 06/29/2007 2:22:12 PM PDT
by USF
(I see your Jihad and raise you a Crusade)

I would guess a liquid oxidizer like H2O2 would work best with a liquid fuel like kerosene, diesel, etc. Flour, of all the things ? I guess the Jihadists have studied the Anarchists Cookbook more thoroughly than anyone else.

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